#Golf R 2015, 60k miles auto
London 🇬🇧
Hi 👋🏽, I'm thinking of doing a oil change but not sure if it's OK to use the remaining 2 litters of oil from last year that's in a previously opened bottle! To mix with a brand new 5 litters I just bought to total 5.7 litters for my Golf R
I know oil left inside a engine can degrade.... even if not driven much within the year. my question is would oil degrade in a bottle also or would it be OK to use/mix with the new 5 litters of oil?
Thanks people 🤗
If there's been no contamination, the main concern is whether the additives package has degraded (which usually takes around 5 years with modern oils). The base oil remains intact and functional but the additives can and do break down. When the additive package breaks down you shouldn't use the oil. Lake Speed allows a simple/best test for to determine whether an oil is still good is to poor it into a clear container and check for any air bubbles https://youtu.be/E1T4XFPgBeo?t=1002
You'll be totally fine mixing oil from last year with new one, especially if it's exact same oil.
